In recent year, in order that an optical module used to an optical access system may make a size smaller and a cost reduce, an application of an optical transmitting and receiving module in which a transmitting operation and a receiving operation are performed together by using an optical waveguide etc. has been in main current. As the background of this, an expansion of a data transmission capacity has been demanded by supporting explosive popularization of the internet. The optical transmitting and receiving module is mounted with both a light emitting element for transmitting light and a light receiving element for receiving light.
In an optical transmitting and receiving module in related art, an optical signal transmitted from an optical fiber is divided by a Y-branching waveguide and transferred to the respective light receiving element and light emitting element (for example, refer to Japanese Unexamined Patent Publication (Kokai) No. 2000-206349 and No. 2002-169043).
Further, the optical transmitting and receiving module which the optical signal received from the optical fiber is transferred via a wavelength selection filter only to the light receiving element has been proposed (for example, refer to Japanese Unexamined Patent Publication (Kokai) No. 2001-133642).
In the optical transmitting and receiving module mentioned in the Japanese Unexamined Patent-Publication (Kokai) No. 2000-206349 and No. 2002-169043, by using the Y-branching waveguide, the optical signal transmitted from the optical fiber is guided to two-branched waveguides in a ratio of one to one respectively. Therefore, when the optical signal is received by the light receiving element, the optical signal is guided to the light emitting element simultaneously. Consequently the optical transmitting and receiving module is not able to transmit the optical signal simultaneously with receiving the optical signal.
The optical transmitting and receiving module mentioned in the Japanese Unexamined Patent Publication (Kokai) No. 2001-133642) can perform simultaneously a transmitting operation and a receiving operation, however the module has to be mounted with a wavelength selection filter or other optical element, so that it has a disadvantage in terms of a cost and productivity.